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Back Print Name Class Date Skills Worksheet Chapter Review USING KEY TERMS The statements below are false. For each statement, replace the underlined term to make a true statement. 1. Electrons have a positive charge. 2. All atoms of the same element contain the same number of neutrons. 3. Protons have no electrical charge. 4. The atomic number of an element is the number of protons and neutrons in the nucleus. 5. The mass number is an average of the masses of all naturally occurring isotopes of an element. UNDERSTANDING KEY IDEAS Multiple Choice ______ 6. The discovery of which particle proved that the atom is not indivisible? a. proton c. electron b. neutron d. nucleus ______ 7. How many protons does an atom with an atomic number of 23 and a mass number of 51 have? a. 23 c. 51 b. 28 d. 74 ______ 8. In Rutherford’s gold-foil experiment, Rutherford concluded that the atom is mostly empty space with a small, massive, positively charged center because a. most of the particles passed straight through the foil. b. some particles were slightly deflected. c. a few particles bounced straight back. d. All of the above Copyright © by Holt, Rinehart and Winston. All rights reserved. Holt Science and Technology 20 Introduction to Atoms Back Print Name Class Date Chapter Review continued ______ 9. Which of the following determines the identity of an element? a. atomic number b. mass number c. atomic mass d. overall charge ______10. Isotopes exist because atoms of the same element can have different numbers of a. protons. c. electrons. b. neutrons. d. None of the above Short Answer 11. What force holds electrons in atoms? 12. In two or three sentences, describe Thomson’s plum-pudding model of the atom. Math Skills 13. Calculate the atomic mass of gallium, which consists of 60% gallium-69 and 40% gallium-71. Show your work below. 14. Calculate the number of protons, neutrons, and electrons in an atom of zirconium-90 that has no overall charge and an atomic number of 40. Show your work below. Copyright © by Holt, Rinehart and Winston. All rights reserved. Holt Science and Technology 21 Introduction to Atoms Back Print Name Class Date Chapter Review continued CRITICAL THINKING 15. Concept Mapping Use the following terms to create a concept map: atom, nucleus, protons, neutrons, electrons, isotopes, atomic number, and mass number. Copyright © by Holt, Rinehart and Winston. All rights reserved. Holt Science and Technology 22 Introduction to Atoms Back Print Name Class Date Chapter Review continued 16. Analyzing Processes Particle accelerators, are devices that speed up charged particles in order to smash them together. Scientists use these devices to make atoms. How can scientists determine whether the atoms formed are a new element or a new isotope of a known element? 17. Analyzing Ideas John Dalton made a number of statements about atoms that are now known to be incorrect. Why do you think his atomic theory is still found in science textbooks? 18. Analyzing Methods If scientists had tried to repeat Thomson’s experiment and found that they could not, would Thomson’s conclusion still have been valid? Explain your answer. Copyright © by Holt, Rinehart and Winston. All rights reserved. Holt Science and Technology 23 Introduction to Atoms Back Print Name Class Date Chapter Review continued INTERPRETING GRAPHICS Use the diagrams below to answer the questions that follow. Electron a. b. Neutron Proton c. Key proton neutron electron 19. Which diagrams represent isotopes of the same element? 20. What is the atomic number for A? 21. What is the mass number for B? Copyright © by Holt, Rinehart and Winston. All rights reserved. Holt Science and Technology 24 Introduction to Atoms Back Print TEACHER RESOURCE PAGE Chapter Review 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Reinforcement A. B. C. D. E. F. G. H. I. J. K. L. Protons protons Neutrons mass number atomic mass C A D A B electromagnetic force Sample answer: The plum-pudding model describes the atom as a lump of positively charged material with negatively charged particles throughout. The positively charged material is like the pudding, and electrons are like plums in it. (0.60 69 amu) (0.40 71 amu) 69.8 amu number of protons atomic number 40 number of neutrons mass number–atomic number 50 number of electrons number of protons 40 An answer to this exercise can be found at the end of the teacher edition. Scientists must determine the atomic number, or the number of protons, in the newly formed nucleus. The nucleus is that of a new element only if the number of protons is different from all known elements. Sample answer: Dalton’s atomic theory was the first one based on experimental evidence. It helps show how a theory develops as new information is discovered. No; the results of an experiment must be repeatable to be considered valid. A and C 3 7 M. N. O. P. Q. R. S. T. Rutherford, 1909–1911 Rutherford, 1909–1911 Thomson, 1897 Bohr, 1913 Dalton, 1803 Thomson, 1897 Democritus, 440 BCE Rutherford, 1909–1911 Democritus, 440 BCE Dalton, 1803 Bohr, 1913 Schrödinger and Heisenberg, twentieth century Thomson, 1897 Rutherford, 1909–1911 Dalton, 1803 Schrödinger and Heisenberg, twentieth century Dalton, 1803 Democritus, 440 BCE Rutherford, 1909–1911 Dalton, 1803 Critical Thinking 1. Because the nucleus is positively 2. 3. 4. 5. 6. charged, the suit also must have been positively charged to create this repulsion. Her suit would have had a neutral charge. Answers will vary according to the forces students discuss. Sample answer: If her suit was positively charged, then the electromagnetic force would pull her toward the electrons in the atom. Knowing that the atomic number of carbon is six, Professor Pending could look for an atom with six protons in its nucleus. An atom’s mass number is equal to its protons plus its neutrons. All carbon atoms have six protons. Carbon-14 would have six protons and eight neutrons. Professor Pending could use this characteristic to identify the correct atom. A negatively charged ion has more electrons than protons. Therefore, the ion would require at least seven electrons. Copyright © by Holt, Rinehart and Winston. All rights reserved. Holt Science and Technology 63 Introduction to Atoms